Known from document EP-B-1312388 is a precision flow regulator comprising a first body having a tubular inlet connector and a second body having a tubular outlet connector.
The first and second bodies are made of moulded plastic material and are coupled to one another in such a way that they can rotate with respect to one another about an axis of rotation, with the interposition of a gasket made of elastomeric material. At least one dosing passage is provided between the first and second bodies and through said gasket to open the communication between said inlet connector and said outlet connector progressively by means of the relative rotation between said first and second bodies. In the flow regulator according to the already cited document EP-B-1312388, the first body has a wall facing the second body, formed with a plurality of dosing grooves, which have differentiated sections and lengths, set concentrically with respect to the axis of rotation and selectable, via the relative rotation between the first and second bodies, to set the inlet connector in communication with the outlet connector through a hole in the gasket made of elastomeric material.
A similar flow regulator, equipped, however, with a single dosing groove with variable cross section, is also described in document U.S. Pat. No. 5,234,413.
For the production of the above flow regulators three distinct operations are required for moulding, normally injection moulding, of the three components (first body, second body and gasket), and then a further operation of assembly. Furthermore, said flow regulators are necessarily equipped with at least one graduated scale, and more typically two graduated scales arranged peripherally along the side wall of the second body, as well as with a pointer associated to the first body and co-operating with the graduated scale or each graduated scale for visualizing the relative angular position between the first and second bodies, corresponding to the selectively set regulation of the flow of liquid from the inlet connector to the outlet connector through the aforesaid at least one dosing passage. The graduated scale or scales and the pointer (not illustrated in the aforesaid prior documents but necessarily present on the flow regulators built according to said documents, as available on the market) require further operations of printing (normally silk-screen printing) to be carried out, respectively, on the first body and on the second body prior to their mutual assembly.